The scaling down of integrated circuit devices has created a need to incorporate high dielectric constant (i.e., high dielectric permittivity) materials into capacitors and gates. The search for new high dielectric constant materials and processes is becoming more important as the minimum size for current technology is practically constrained by the use of standard dielectric materials. Dielectric materials containing alkaline earth metals can provide a significant advantage in capacitance compared to conventional dielectric materials. For example, a perovskite material, strontium titanate (SrTiO3), has a disclosed bulk dielectric constant of up to 500.
Unfortunately, the successful integration of alkaline earth metals into vapor deposition processes has proven to be difficult. For example, although atomic layer deposition (ALD) of strontium β-diketonates has been disclosed, the poor reactivity of these precursor compounds often requires high substrate temperatures and strong oxidizers to grow a film, which is often contaminated with carbon-containing impurities. Carbon-containing impurities such as strontium carbonate, for example, are undesirable because the impurities can substantially lower the dielectric constant of the resulting film. Efforts to remove such carbon-containing impurities from high dielectric constant films have met with limited success due at least in part to the inconvenient and/or expensive technologies that have been employed, including, for example, exposure to ultraviolet (UV) radiation in ozone, and high pressure isotropic reactive ion etching.
New methods of preparing high dielectric constant films are being sought for current and new generations of integrated circuit devices.
The following description of various embodiments of the methods as described herein is not intended to describe each embodiment or every implementation of such methods. Rather, a more complete understanding of the methods as described herein will become apparent and appreciated by reference to the following description and claims in view of the accompanying drawing. Further, it is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.